slide a steel ring (collar) onto the tubing, insert a
install gas-supply service pipes. A plumber will
ribbed brass connector into the flexible tubing
install gas shutoff valves to gas-supply stubs;
and then use a crimping tool to compress the ring short lengths of flexible gas-supply pipe run from
P R O T I P
and squeeze the tubing tight to the connector.
there to a fixture.
have a friend help you set
Push fit. Also known as a slip-in fitting, this
plastic Dwv pipe. although plas-
employs a mechanism with tiny, stainless-steel
CPVC Supply
tic is light, it is cumbersome.
teeth inside. Square-cut the end of the tubing,
Most plumbing codes allow CPVC for hot- and
once you’ve applied pipe cement,
and push it firmly into the fitting until it seats.
cold-water lines, but check with local authorities
you have about 30 seconds to
You then slide a collet forward to secure the
to be sure. CPVC is a good choice for hard-water
position the fittings before it
tubing. This fitting has the benefit of being
areas because—unlike copper—CPVC won’t be
sets. with two people working,
reusable—just slide the collet and pull out the
corroded by chemicals in the water. Note: CPVC
one can hold a fitting while the
tubing—though it’s advisable to cut a new end if
is a different material from PVC, which is widely
other pushes the pipe and twists
you remove the tubing more than once.
used as drain and waste pipe; PVC may not be
it one-quarter turn.
Compression fitting. Compression fittings are
used as supply pipe, however, because it releases
well known to anyone who’s ever connected a
carcinogens.
chrome supply riser to a lavatory or to a toilet
Working with CPVC supply pipe is much like
tank. Insert the end of the PEX tubing into the
cutting and joining plastic DWV pipes, explained
fitting sleeve, then tighten the nut of the threaded at some length later in this chapter. The main dif-
fitting. Specialized compression fittings can join
ference is that waste pipes are larger. Briefly,
different pipe materials.
here’s how to join CPVC: Cut the pipe ends
square using a plastic-pipe saw or plastic-pipe
PeX fittings. Because PEX is flexible, you need
cutting shears. Clean the pipe ends as well as the
far fewer fittings. But you do need some, espe-
inside of the fitting. Next, apply solvent-based
cially if you want to tie PEX into existing supply
cement to each. Insert the pipe into the fitting,
pipes. So, as is the case with copper fittings,
turning either the pipe or the fitting a quarter
there’s a slew of PEX fittings and adapters that
turn in one direction only to spread the cement.
enable you to connect PEX to rigid copper or
Finally, allow the glued joints to set adequately
CPVC plastic. Some change pipe materials, size
before putting pressure on the line.
and direction, such as a 3⁄4-in. copper by 1⁄2-in.
Before installing CPVC, make sure that you
PEX 90 (also called a reducing ell). There are also have the adapters needed to join the new plastic
PEX-specific pieces such as the plastic support
pipes to existing metal pipes and fixtures.
elbow shown at left that prevents the tubing from
collapsing when it must make a sharp turn. Point
being, whatever you need your pipes to do, just
DWV Materials
ask your plumbing supplier: There’s probably a
ABS and PVC plastic pipe are by far the most
fitting for it.
common materials for drainage, waste, and vent-
Note: If you do join PEX to a sweated copper
ing lines, although cast iron is still specified
fitting, solder the copper parts and allow them to where sound suppression is important. Plastic
cool before attaching the PEX.
pipe is strong, the most corrosion resistant of any
DWV pipe, and it’s easy to cut and assemble
Galvanized Steel Pipe
using special solvent-based cements. It’s light
enough for one person to handle, reasonably
Galvanized pipe corrodes and constricts, reduc-
PeX tubing does require specialized
priced, and extremely slick inside, which ensures
ing flow and water pressure, so it is no longer
fittings, such as plastic support
a good flow of wastes.
installed as water-supply pipe. If your existing
elbows at tight bends and proprietary
It’s by far the favorite DWV material of ama-
clamps where tubing is attached to
system is galvanized and the water flow is weak,
teur plumbers—and many pros. But there are a
metal stub-outs.
replace it as soon as possible. If you’re not quite
few disadvantages. Many codes prohibit using
ready to rip out and replace all of your galvanized plastic pipe outside because of durability and UV
pipe, you can replace or extend sections with
degradation issues, and if you don’t spread the
rigid copper. However, you must use a dielectric
cement evenly or allow it to cure before stressing
union (see the bottom photo on p. 323) to join
the joints, plastic can leak.
copper sections to steel. Otherwise, electrolysis
330 Chapter 12
zzzzzz Dwv Fitting sampler
ELBOWS
TEES OR TEE FITTINGS
Ell or 90
Vent ell
Street ell
Sanitary tee
Vent tee
Long-sweep ell
221⁄2° ell
45˚ ell or 45
Reducing tee
Closet bend
Double tee or cross fitting
or 4x3
POTPOURRI OF PARTS
WYE FITTINGS
P-trap (required for
all fixtures except a toilet)
Wye fitting
Trap adapter has a
slip-nut coupling
with a plastic washer
Double wye
Closet flange, which
Cleanout adapter
glues to a closet bend
Combo (or tee/wye)
(drawing exaggerates
sweep)
Cleanout plug
Coupling
The fittings shown are ABS plastic, but their shapes are essentially the same as those of copper and cast-
iron DWV fittings of the same name. Drain fittings—such as the long-sweep ell, the combo, and the sanitary
tee—turn gradually so wastes can flow freely, without clogging. Vent fittings have tighter turning radii
because they carry only air. Finally, street fittings have one hubless end that fits directly into the hub of
another fitting, which is useful when space is tight.
plumbing
331
Cast iron is relatively corrosion resistant,
though it will rust in time (decades), and its mass
heat-recovery draiNS deadens the sound of running water. Although it’s
heavy to work with, it is s
till specified by many
as their name suggests, heat-recovery drains (HRds) capture some of the heat that
professionals for high-end jobs, where codes
goes down the drain when you shower, do the dishes, or wash clothes. The heart of an
allow pipes on building exteriors, and where
HRd is a special drain wrapped with hollow copper coils that acts as a conductive heat
codes require cast iron in multistory buildings.
exchanger. as heated water runs down the drain, it preheats clean water running
Ever since no-hub couplings replaced lead and
through the coils. That preheated water can then go directly to a fixture, to a tradi-
oakum, cast iron has been easier to connect, but
tional water heater, or to a separate storage tank. already preheated, that water takes
it still takes skill and strength to cut cleanly and
less energy and so costs less to bring to the desired temperature. HRd technology is
support adequately. Consequently, it’s rarely
certain to change, but it seems most energy-efficient if its preheated water feeds a
installed by amateur plumbers. Professionally
tankless, on-demand water heater. creating a near instantaneous heat transfer while
installed cast-iron systems cost, on average, 40%
someone is, say, showering, there is no need to store the preheated water in a tank,
to 50% more than plastic-pipe installations.
Copper DWV pipe is installed mostly on jobs
where it would require additional energy to keep its temperature constant.
with bottomless budgets. Copper is lightweight,
durable, and undeniably handsome. Because its
walls are relatively thin, copper DWV pipe is
sometimes specified where there are tight turns.
However, copper costs two to three times as
zzzzzz how an hrD works
much as a plastic DWV installation, and it’s less
corrosion resistant. Compared with cast iron,
copper’s thin walls don’t suppress sound nearly
as well.
Hot
water
Preheated cold water to
plasTIC Dwv pIpe
a plumbing fixture or to a
water heater
Cut ABS or PVC pipe with a plastic-pipe saw and
a miter box, or with a wide-roll pipe cutter. If you
Heat
use a cutter, gradually tighten its cutting wheel
exchanger
after each revolution. Whatever tool you use to
cut the pipe, use a utility knife, a rounded file, or
a deburring tool to clean off burrs before sanding
Cold water in
the cut lightly with emery paper. Use a clean
cloth to wipe off any grit.
Dry-fit the pipes and fittings before cementing
them together. Dry-fitting allows you to deter-
Hot-water
Drain water
mine the exact direction you want the fitting to
tank
point, as well as the depth of the pipe’s seat in the
fitting. Pipe cement sets so quickly that there’s no
time to fine-tune fitting locations. Use a grease
pencil or a builder’s crayon to draw alignment
marks on the pipe and the fitting; a yellow or
white grease pencil works well on black ABS
pipe, as shown in the bottom left photo on the
facing page. Then take apart the dry-fit pieces
P R O T I P
and apply the cement.
Apply plastic-pipe primer to the outside of the
Don’t use aBs cement on pvC
pipe and to the inside of the fitting. Then, using
pipe or vice versa. Because sol-
the cement applicator, apply a generous amount
vent-based cements partially dis-
solve plastic to create a chemical
of solvent-based cement to the outside of the pipe
weld, their chemistry is quite
and the inside of the fitting hub. Immediately
specific. using the wrong cement
insert the pipe into the fitting so that it seats
or joining pvC and aBs pipe is a
completely. Then turn the fitting (or the pipe) a
code violation because it can
quarter turn in one direction only—stop when the
lead to weak joints and leaks.
alignment marks meet. When you are finished,
the joint should have an even bead of cement all
332 Chapter 12
after dry-fitting dWV pipes and putting alignment marks
on the pipes and fittings, disconnect them and apply
solvent-based cement to the outside of pipes and the
inside of fittings. Wear plastic gloves to protect your skin.
dWV pipe supports. Clockwise from left: riser clamp (stack clamp), steel rigid pipe strap (u-clamp),
aBS pipe strap hanger, and J-clamp (often used with all-thread rod).
Insert cemented plastic pipes all the way into the fitting,
and give a quarter turn to spread the cement evenly. The
yellow crayon lines are the alignment marks.
around. Allow the joint to set completely before
putting pressure on it.
One-coat, no-primer plastic-pipe cements are
new to the market: They seem promising but as
yet are unproven for the long haul. Research
them carefully before you commit.
CasT Iron
To the inexperienced eye, all cast iron looks the
same, but it’s not. If you lightly rap most cast iron
with a rubberized tool handle, you’ll hear a muf-
fled thud; old “light iron,” however, will reverber-
ate somewhat, with a higher, tinny tone. If you
suspect that you have light iron, which was widely
installed in the northeastern United States until
the 1940s, hire a plumber to have a look and, if
necessary, make any cuts you’re planning. If you
Here, two horizontal aBS lavatory drains meet at a figure-5 fitting, also called a double combo. an
aBS vent rises out the fitting’s top hub, while the drain hub connects to a cast-iron stack via a
try to cut light iron with a conventional snap cut-
no-hub coupling. a riser clamp supports the bottom of the cast-iron pipe, and steel nail plates
ter, the pipe may crush and collapse.
protect the aBS.
To cut into cast iron to extend a DWV system
or replace a corroded fitting, rent a snap cutter.
Many cast-iron joints are hubbed, in which a
straight pipe end fits into the flared hub. But
increasingly, sections of straight pipe are joined
via no-hub couplings with inner neoprene
sleeves, as shown in “Splicing a Branch Drain to
plumbing
333
stack admits air and never carries water, it’s a
vent stack.
Most of the venting options described next are
examples of dry venting, in which a vent stack
never serves as a drain for another fixture. But
there are hybrids; for example, if a vent stack
occasionally drains fixtures above it, it is a wet
vent. Wet vents must never carry soil wastes, and
many local codes prohibit all wet venting. But
when it’s legal and the vent is one pipe size larger
than normal to ensure a good flow, wet venting
can be safe and cost effective because it requires
fewer fittings and less pi
pe.
BaCk venTIng
Back venting (also known as continuous venting)
is the dry-venting method shown on the facing
page, and it’s acceptable to even the strictest
a cast-iron snap cutter has beveled
codes. All the fixtures in the drawing have a
cutting wheels along the length of
branch vent. In a typical installation, the trap
its chain.
a Stack” on p. 339. The new pipe–fitting assembly arm of, say, a lavatory empties into the middle leg
should be 1 in. shorter than the cutout section.
of a sanitary tee. The branch drain descends
Before cutting into cast iron, however, sup-
from the lower leg, the branch vent from the
port the pipe on both sides of the intended cut to
upper. When a branch vent takes off from a rela-
prevent movement, which could weaken joints.
tively horizontal section of drainpipe, the angle
Use stack clamps (riser clamps) if you’re cutting
at which it departs is crucial. It may go straight
into a vertical section of pipe. Use strap hangers
up or it may leave at a 45° angle to work around
(see the top right photo on p. 333) if cutting into
an obstruction. But it must never exit from the
a horizontal section. Mark cutlines on the cast
iron with a grease pencil. Then wrap the snap-
cutter’s chain about the pipe, gradually tighten-
ing until the chain is snug and the tool’s cutting
NO-HuB Couplings
wheels align over the cutlines. Crank the cutter’s
handle to continue tightening the chain until the
No-hub couplings (also known as banded cou-
pipe snaps cleanly. Make the second cut, and
plings, band-seal couplings, and hubless con-
remove the old pipe section. Caution: Wear gog-
nectors) consist of an inner neoprene sleeve,
gles during this operation.
which fits over the pipe ends or fittings, and an
Once the cuts are complete, slide the neo-
outer corrugated metal shield, which is drawn
prene sleeve of a no-hub coupling over each
tight by a stainless-steel band clamp. No-hub
remaining pipe end. You may need to roll each
couplings are widely used to join cast-iron pipe
No-hub couplings. at the upper left,
sleeve back on itself, as you would roll up the
a transition coupling joins dWV pipes
and no-hub fittings in new construction, but
cuffs of a long-sleeved shirt. Insert the transition
with different exterior diameters, a
Renovation 4th Edition Page 77